People

Fine-tuned sensors

Graduate student Tracy Tsai is developing a fast and precise system for tuning lasers to emit certain frequencies of light for use in environmental monitoring and medical diagnostics. Tsai’s system, created with electrical engineer Gerard Wysocki, sweeps across a swath of the mid-infrared spectrum 1,000 times a second, which allows monitoring of chemicals in turbulent environments such as a smokestack or exhaled breath. She tested a system similar to the one shown here to detect trace amounts of ammonia, which indicates kidney dysfunction or other disorders when present in a person’s breath. In early 2010, Tsai is spending three months at the Rutherford National Labs in England to collaborate on further tunable laser work. The work is part of Mid-Infrared Technologies for Health and the Environment (MIRTHE), a major National Science Foundation center based at Princeton. Apart from her research, Tsai serves as outreach officer for the Graduate Women in Science and Engineering student group. (Photo by Volker Steger)

Scaling a great bridge

Sylvester Black, who graduated in 2009, worked with Maria Garlock, an assistant professor of civil and environmental engineering, to design a 92-foot replica of the Golden Gate Bridge. The model will be the centerpiece of an exhibit scheduled to open at the south base of the bridge in 2012, the Golden Gates’ 75th anniversary. The bridge was completed in 1937 after Princeton Engineering professor George Beggs made and tested a scale model of the tower to affirm its soundness. Black previously worked with Garlock and legendary bridge expert David Billington ’50 to make models of graceful structures designed by Félix Candela for an exhibit that was displayed at Princeton and the Massachusetts Institute of Technology. (Photo by Frank Wojciechowski)